Sergio Best’s scientific contributions

... We do, however, expect only a small second-order effect from this interplay. Finally, the analysis will be further verified using information about the SO SATs beam chromaticity obtained by employing drone-borne calibrators [9,10,17,35] an effort that already started in December 2024. ...

Reference:

The Simons Observatory: Quantifying the impact of beam chromaticity on large-scale B-mode science

... The resulting cosmic birefringence would lead to a nonvanishing EB correlation as would polarized Galactic foregrounds (Planck Collaboration et al. 2016c), which would be degenerate with a miscalibration of detector polarization angles. Hence, CMB experiments are developing alternative methods, e.g., using the Crab Nebula (Tau A; Aumont et al. 2020;Sobrin et al. 2022) or polarized Galactic foregrounds (Minami et al. 2019;Minami & Komatsu 2020), artificial polarization calibration sources (Ade et al. 2015;Nati et al. 2017;Dünner et al. 2020;Cornelison et al. 2022), or map-based deprojection (St Germaine et al. 2020) to calibrate the detector polarization angles. Polarization rotations induced by the optics can also be modeled using polarizationsensitive ray tracing software (Koopman et al. 2016). ...

Reference:

Cosmology Large Angular Scale Surveyor (CLASS): 90 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance